One system for reading information on a recorded disk, for example, includes using an optical pickup for radiating laser light onto a recording surface of a disk and demodulating the light reflected by or transmitted through the disk. In such a system there is provided a so-called tracking servo means acting as a find adjustment means in order to suitably control a quantity of biasing of an actuator (such as a tracking mirror for defecting the irradiation light) so that the irradiation light correctly tracks a recorded track.
Since an adjustment range of the tracking actuator is narrow a so-called slider servo means is also provided as a rough adjustment means for driving a slider motor to control a rough radial position of the pickup relative to the disk.
In order to search for recorded information in a short time, it is necessary to cause a pickup to perform a so-called jump operation so that an information detecting point of the pickup moves to jump over a plurality of tracks. In an apparatus for performing this jump operation, one suitable approach is as follows:
After a tracking servo loop and a slider servo loop are opened and a driving signal is externally applied to a tracking actuator to thereby deviate the tracking actuator, the tracking servo loop and the slider servo loop are closed so that the slider motor is driven according to a quantity of deviation of the tracking actuator.
A jump operation control apparatus using the above approach is disadvantageous in that it is difficult to repeatedly perform a so-called multi-jump operation so that the information detecting point jumps over a plurality of tracks because the setting of the slider servo means is slow; as a result of the foregoing disadvantage, it is impossible to shorten the time required for searching for information.